'56 Duntov cam

[hzt7n4]

Could the optional "Duntov" solid lifter cam be ordered with a powerglide? Or would this combination have been assembled after it left the factory?

 

[WayneC]

Can't give you a definitive answer except to say the NCRS spec guide says the 225hp engine option was a pre-req for the "special cams" installed by the factory, and slightly over half the 225hp option cars sold (3,080) were equipped with powerglide. My guess is that most, if not all, the cam cars (111) were sold to racers with an inside connection to Chevy and thereby likely were on cars with manual transmissions. But, the cam was a standard option supposedly available to the public, so I do not know whether any powerglide cars were actually sold to the public with the cam, nor do I have reason to think they were restricted to cars with manual transmissions... ie, if the 225 hp cars were sold with Powerglide, why not the 270hp?? ...except, of course, for the possibility of low vacuum interfering with proper Powerglide shifts.

If the answer exists, it probably is in Noland Adams' Vol 1, but I'm away on vacation and don't have access to my copy.

 

[hzt7n4]

Thanks Wayne. My thoughts as well. I have a '56 with the FG engine code with a Powerglide. It's been in thr family since 1961. I can recall going to the dealership with my father and watching the mechanic adjust the lifters. Something that is not usually done with hydraulic lifters.
The engine was rebuilt by my father years ago and it did indeed have solid lifters. The car has an interesting assortment of options, one being the cam with the FG engine. Radio delete though.

Thanks again.

 

[67HEAVEN]

hzt7n4,

Welcome to the . We're glad to have you and your car here.

Drop by the New Member Introductions area and introduce yourself.

 

[vettefinderjim]

2 camshafts were used in 56 CORVETTES

Could the optional "Duntov" solid lifter cam be ordered with a powerglide? Or would this combination have been assembled after it left the factory?

In 56, they used two camshafts in Corvettes .
Both hydraulic lifter and mechanical lifter camhafts were used in passager 265 V-8 motors.
Both the 210hp, single four motor and 225hp 2x4 carburator engine used a # 3711354 (casting#3711355) mechanical camshaft. It had a intake and exhaust lift of .404 and .413 and the duration of 264 intake and 266 exhaust.

Both motors could be ordered with manual or automatic powerglide transmission.

The 240hp engine, which appeared late in production used notched pistons for greater ease of no valve interferance and the new 3734077 cam (casting #3734078) It had the same intake and exhaust lift of .404 and .413, but the duration was increased to 287 degrees on both intake and exhaust. Only 111 of thses cars were made and all were manual transmission models.

The famous "DUNTOV" cam is the 1957 unit, a mechanical lifter design, part # 3736097(casting # 3736098). It was used in 270hp and 283hp fuel injection cars and Corvettes in 57 and continued up thru the 1963 model year of high performance solid lifer Corvettes. Notice its lift was .394 and.400, which was a little less than the 240hp cam used in 56.The 287 duration is the same. I remember in 56 there were some problems with valve interferance with piston tops when this cam first appeared. By 57, the engineers figured it out with notched pistons used on 270 and 283 hp engines, and pop up higher compression pistons used on the 283 hp engine only.

 

[WayneC]

Good info, Jim... on closer examination of the NCRS spec guide, the engine stamp suffix is "GU" for a 240hp order code 449 (the "special cam" engine) which ONLY came with the 3-speed manual... as opposed to "FG" suffix (225hp code 469) with Powerglide, or "GR" (225hp code 469) with 3-speed. I think that is definitive info that the 111 "special cam" cars all had manual 3-speed trannies.